Swedish patent application No. 7909781-2 discloses an apparatus for mixing treatment chemicals in suspensions. The apparatus comprises a mixing means consisting of a cylindrical portion provided with axial ribs, and of a larger discshaped portion provided with radial ribs. The housing of the apparatus is provided with corresponding stationary ribs. When the mixing means rotates the pulp flowing through the passages between the mixing means and the housing is fluidized and chemicals are efficiently mixed in the pulp.
U.S. Pat. No. 4,410,337 discloses an apparatus for separating gas from a fibre suspension, in which the fibre suspension is caused to rotate by a rotor provided with blades and disposed in the inlet channel of the apparatus so as to bring about a core of gas surrounded by fibre suspension, gas being discharged from the core to a separate gas space.
Further, Finnish patent application No. 823279 discloses an apparatus for mixing chemicals in fibre suspensions. The apparatus comprises a rotor provided with external protrusions and disposed in the casing in the inlet channel of the centrifugal pump in front of an impeller. The casing is provided with an opening or openings through which chemicals can be supplied to the space between the inlet channel and the rotor.
Until now at least two devices provided each with its own drive have been required for pumping pulp, removing the harmful gas and mixing chemicals in the pulp.